How can I drive a servo motor on the BeagleBone Blue using Nerves?
Do I need to add a device tree overlay for PWM support in a custom Nerves system?
There are premade BeagleBone device tree overlays are located in /lib/firmware, and there is likely one for PWM. This means you don’t have to create a custom Nerves system unless you want to. The overlay can be applied at runtime with the BeagleBone config-pin utility (see this elixir wrapper), or applied to the Nerves system by adding the overlay to provisioning.conf.
The easiest way to drive servos is to use an I2C servo controller. That way you could use circuits_i2c.
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Thanks for the reply.
I have a PCA9685-based Adafruit 815 that I decided to try.
I found hex package pca9685, and was able to get my motor working using it.
I was using a RPi4 when I got it working.
I was also able to get it to work using a BeagleBone Black.
I want to get it working on a BeagleBone Blue.
I believe the Blue is basically a BB Black with an integrated robotics cape, which has a 12V power supply, and is able to drive motors without running external power.
I soldered a JST SH 1.0-4 Pin connector to the Adafruit servo driver board.
I did the same with a spare servo driver board as well.
I tried these commands:
{:ok, ref} = Circuits.I2C.open("i2c-2")
Circuits.I2C.write(ref, 0x40, <<0x00, 0x10>>)
The response is:
{:error, :i2c_nak}
Could the Blue need some adjustments to the device tree configurations? The I2C initialization?
I might test running debian/raspbian on the Blue to see if I can get i2c communiate.
Thanks
I’m trying the PWM approach at the moment.
Running it on the Blue would be ideal a single power source can power the board and the motor. Plus it has 8 servo outputs on the board.
I went down some rabbit holes with AI, but have not been able to get anything to show up under /sys/class/pwm/
I see the following under /lib/firmware that look helpful
BB-PWM0-00A0.dtbo
am33xx_pwm-00A0.dtbo
BB-PWM1-00A0.dtbo
BB-PWM2-00A0.dtbo
PB-PWM-TIMER-P1.20.dtbo
PB-PWM-TIMER-P1.26.dtbo
PB-PWM-TIMER-P1.28.dtbo
PB-PWM-TIMER-P2.27.dtbo
PB-PWM-TIMER-P2.31.dtbo
